I believe that you've got a repo that has no namespace pair. Most of your packages have the namespace pair, but this one, as well as a few others, don't.
[id:cee0de03-7068-4e9b-92a3-9d522d28846b, location:https://raw.githubusercontent.com/kkossev/hubitat-muxa-fork/master/drivers/zemismart-zigbee-multigang-switch.groovy, name:Zemismart ZigBee Wall Switch Multi-Gang, required:true]
[id:4780297c-060a-44c1-b071-4e7d08e88936, location:https://raw.githubusercontent.com/kkossev/Hubitat/development/Drivers/Tuya%20Zigbee%20mmWave%20Sensor/Tuya_Zigbee_mmWave_Sensor_lib_included.groovy, name:Tuya Zigbee mmWave Sensor, required:true]
[id:39945711-acb5-420b-a3ce-6ec89772f4cf, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Aqara%20Cube%20T1%20Pro/Aqara_Cube_T1_Pro_lib_included.groovy, name:Aqara Cube T1 Pro, required:true]
[id:cad2820a-82ad-4329-923d-0a4ccb885355, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Zigbee%20Button%20Dimmer/Zigbee_Button_Dimmer_lib_included.groovy, name:Zigbee Button Dimmer, required:true]
[id:7862fa83-0a21-46a9-b256-819e1f98a28b, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Tuya%20Zigbee%20Control%20Screen%20Panel/Tuya_Zigbee_Control_Screen_Panel_lib_included.groovy, name:Tuya Zigbee Control Screen Panel, required:true]
[id:76494db0-9166-4c07-911f-c3bd37d81d7c, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Tuya%20Zigbee%20Fingerbot/Tuya_Zigbee_Fingerbot_lib_included.groovy, name:Tuya Zigbee Fingerbot, namespace:kkossev, required:true]
[id:551e8d69-6ce0-4986-b336-ae9cc0c8afd9, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/VINDSTYRKA%20Air%20Quality%20Monitor/VINDSTYRKA_Air_Quality_Monitor_lib_included.groovy, name:VINDSTYRKA Air Quality Monitor, namespace:kkossev, required:true]
[id:71ef9bd1-82ac-4c1d-b986-444b4cfbc8a7, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Tuya%20Zigbee%20Light%20Sensor/Tuya%20Zigbee%20Light%20Sensor.groovy, name:Tuya Zigbee Light Sensor, namespace:kkossev, required:true]
[id:18f500cd-fe3e-45fa-8b9d-2c17089c7d7f, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Apps/Device%20Health%20Status.groovy, name:Device Health Status, namespace:kkossev, oauth:false, primary:false, required:true]
[id:ea11eefa-641f-440c-9f4e-e4d921e3204f, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Tuya%20Contact%20Sensor/Tuya%20Contact%20Sensor.groovy, name:Tuya Zigbee Contact Sensor++ w/ healthStatus, namespace:kkossev, required:true]
[id:46d6d06d-00cc-4bf5-9931-b2655e66bfa1, location:https://raw.githubusercontent.com/kkossev/Hubitat-SiHAS/main/sihas_dualmotionsensor_dms300zb.groovy, name:SiHAS Dual Motion Sensor, namespace:shinasys, required:true]
[id:ee7b47fe-5344-401b-be3d-2050143564c9, location:https://raw.githubusercontent.com/kkossev/Hubitat-SiHAS/main/sihas_doorlock_dlm300z.groovy, name:SiHAS ZigBee Lock Without Codes, namespace:shinasys, required:true]
[id:d5c3b85e-d198-451c-b4cb-0d5aea6f231b, location:https://raw.githubusercontent.com/kkossev/Hubitat-SiHAS/main/sihas_peoplecounter_csm300zb.groovy, name:SiHAS People Counter, namespace:shinasys, required:true]
[id:fed274c7-4f62-4f0b-91de-73b3fdb5af9b, location:https://raw.githubusercontent.com/kkossev/Hubitat-SiHAS/main/sihas_powermeter_pmm300z.groovy, name:SiHAS Zigbee Power Meter, namespace:shinasys, required:true]
[id:95fd080b-c541-4426-a849-247a3678945b, location:https://raw.githubusercontent.com/kkossev/Hubitat/main/Drivers/Tuya_Zigbee_Smoke_Detector/Tuya_Zigbee_Smoke_Detector.groovy, name:Tuya Zigbee Smoke Detector, namespace:kkossev, required:true]
Those in the top segment do not have namespace, those in the bottom do. The namespace value is case sensitive when comparing. I can see that my own namespace values are inconsistent. I have 3 namespaces when I intended to have only one. I have "csteele", "cSteele" and "csteele-PD"
The Package using "cSteele" would appear in the MatchUp result. I changed that "cSteele" to be "csteele" out in the repo, but then that package never came up during MatchUp. I put the typo back into the repo and it returned to the MatchUp result.
What that says is that the namespace value in the HPM internal Manifest storage must exactly match the namespace in the Repo for Matchup to propose it as a match.
The HPM namespace value for this specific Package is:
[id:2077, title:Zemismart ZigBee Wall Switch Multi-Gang, namespace:muxa]]
As you pointed out, HPM is comparing package name AND namespace BUT not of the Source Code. The compare is only between the installed package's HPM Manifest entry and the repo json.