Heya,
Per EA/Respawn's post on Cross Progression:
Note: stats cannot be merged across platforms, so they will default to your primary profile. Any badges tied to stats from other profiles merged into your EA Account may not be available.
[EA] Apex Legends - Cross Progression
Ranked badges would fall under this.
The primary account before the merge would have been the account with the highest level from a certain platform. This means that badges from that platform would have been retained.
Assuming you still have the Season 8 Ranked Badge, but not the Season 10 Master badge, it's likely that your PlayStation account was the primary account before Cross Progression rolled out, whilst losing the stats, and therefore those badges from the Steam platform.
This was likely done due to limitations, as they would not be able to merge those stats.
Sadly enough, Respawn/EA does not grant badges for such lost data, so there is no way to get it back, even if you go through EA Support. This was one of the compromises they had to make to roll out cross progression, and in turn, a lot of players have lost a decent chunk of their badges / stats if they played a lot between 2 platforms.
