I mean ultimately both companies have invested R&D into building their SDKs and it comes across as bizarre to me to suggest that one company should be legally banned from charging licensing fees for their use.
But if we've decided that it's unhealthy to allow dominant tech firms to tax everyone for access to their platforms...
Then an SDK might become the final area where they attempt to do so.
It'd certainly be a lot cleaner if there were 2 SDKs: a base, primitive-only freely licensed one with the bare minimum for interacting with all platform components and a higher-level, premium paid one that had better DX.