luceos I haven't encountered an issue like this with the Flarum.org extension marketplace I'm currently working on. In fact, when you mentioned a Packagist-related update issue a few days ago, I didn't experience any problems either.
If it's not something that needs to remain confidential, could you briefly explain how you determine which Flarum version an extension is compatible with? Perhaps the method I'm using is more effective, and I could explain how I've designed it. It automatically tracks Flarum updates and immediately processes compatibility information for older extensions.
At the moment, Flarum.org stores extension compatibility data like this:
{"2.0.0-rc.2":true,"2.0.0-rc.1":true,"2.0.0-beta.8":true,"2.0.0-beta.7":true,"2.0.0-beta.6":true,"2.0.0-beta.5":true,"2.0.0-beta.4":true,"2.0.0-beta.3":true,"2.0.0-beta.2":true,"2.0.0-beta.1":true,"1.8.16":true,"1.8.15":true,"1.8.14":true,"1.8.13":true,"1.8.12":true,"1.8.11":true,"1.8.10":true,"1.8.9":true,"1.8.8":true,"1.8.7":true,"1.8.6":true,"1.8.5":true,"1.8.4":true,"1.8.3":true,"1.8.2":true,"1.8.1":true,"1.8.0":true,"1.7.2":true,"1.7.1":true,"1.7.0":true,"1.6.3":true,"1.6.2":true,"1.6.1":true,"1.6.0":true,"1.5.0":true,"1.4.1":true,"1.4.0":true,"1.3.1":true,"1.3.0":true,"1.2.1":true,"1.2.0":true,"1.1.1":true,"1.1.0":true,"1.0.4":true,"1.0.3":true,"1.0.2":true,"1.0.1":true,"1.0.0":true,"0.1.0-beta.16":false,"0.1.0-beta.15":false,"0.1.0-beta.14.1":false,"0.1.0-beta.14":false,"0.1.0-beta.13":false,"0.1.0-beta.12":false,"0.1.0-beta.11.1":false,"0.1.0-beta.11":false,"0.1.0-beta.10":false,"0.1.0-beta.9":false,"0.1.0-beta.8.2":false,"0.1.0-beta.8.1":false,"0.1.0-beta.8":false,"0.1.0-beta.7.2":false,"0.1.0-beta.7.1":false,"0.1.0-beta.7":false,"0.1.0-beta.6":false,"0.1.0-beta.5":false,"0.1.0-beta.4":false,"0.1.0-beta.3":false,"0.1.0-beta.2":false,"0.1.0-beta":false}