If I get launched and after the knockback wears off but im still in the tumbling state I am unable to air dodge. I have to perform another move before being able to air dodge. I am unable to give evidence as I can't record and screenshots wouldn't show much.

That is an intended feature, not a bug. The devs want you to actually DI to get out of combos and not just mash airdodge like a maniac like you can in a certain official Smash game.

games

Its successor allows it too.

Used to smash games, unsure if it was a bug or not. Better to post it just in case it was a bug.

I noticed this too. I understand how this would encourage players to DI out of combos, but if a combo isn't true, then air dodging out should be an option. Without airdodging, certain kill confirms (especially ones involving up air) are way too consistent. It should be the attacker's responsibility to read air dodges, rather than the other not having the option to air dodge at all. Also, air dodging is the safest option for simply exiting the tumble state after being knocked away, but the only options available are jump and attack, both of which are punishable.