The theory would be Goku not going all out vs Son Gohan and using a kind of match level... And only displaying his post Karin level when defeating Kuririn, which couples with Tsuru saying "now I see how Tao was defeated"... There all of the team never knew the true level of power Goku post Karin indeed had.
Ofc it's a theory and it could be said right there Goku didn't ise FP vs Gohan. It likely would be said. But Idk, the Tsuru acknowledgement of Goku > Tao after Kuririn's defeat as well as Roshi saying Goku may have surpassed him already at the same moment gives a real vibe of Tao ~ 22nd Budokai Roshi. And there's also Goku stating "now he sees Tenshinhan wants to kill him, then he will go all out". He knew Tao wnated to kill him... The match with Son Gohan was a Budokai match... Once Goku had his tail taken off, he changed expressions and said "now I'm mad!!" and Gohan gave up, so maybe Goku would show more of his "defeating Tao's power there", plus Gohan said he was "absolutely no match vs Goku", while the fight seemed even until Goku used the KMHMH, so maybe Gohan realized Goku had power to spare.
I just find it hard to get around Tenshinhan ans Tsuru saying it was sheer luck Tao was defeated by one of Kame students when Ten and Tsuru saw right then Yamcha's powers. I used to think Chappa was indeed >> Tao, but with all the focus Tao got later on, I already think of Tao >> Kuririn and Yamcha a likely scenario the narrative was pushing there... Even more with the power Goku using to defeat Kuririn being the nail in the coffin for Tsuru to acknowledge and finally see how his borther could indeed have been defeated. I think the narrative leaned heavily towards that.
Like:
Goku (21st Budokai) 20
-- vs Blue 22
Mummy 22
Akkuman 26
Son Gohan 33
Goku (vs Gohan) 34
Chappa 34
Chaozu 38
Yamcha 39
Kuririn 40
Tsuru 45
Kame-Sennin 50
Tao Pai Pai 50
Goku (true power post Karin, full match level vs Kuririn) 55
Tenshinhan 64
Goku (battle level) 66
Tambourine 55
Yajirobe 60
Drum 75
Less than half old Piccolo : 82
-- 100% : 166
Young Piccolo : 225
Goku (post water) : 228
Goku would have gotten overall a 1.2x boost training for the Budokai which seems puny, but who knows, maybe he developed other things like fight awareness, instinct, knowledge like when he outsmarted and surprised Ten many times in the fight
23rd
Cyborg Tao 150
Yamcha 166
Kuririn 185
Tenshinhan 280 (assuming he was a little suppressed when the scouter read him... He was already more knowledgeable in chi than the others and it also helps putting more of a distance between him and Kuririn at the EoZ when the gap at the 23rd was implied as pretty big. Kuririn said Tenshinhan "wasn't normal" when watching him fight Goku. And he was even in power with weighted Goku in the 23rd, so since weighted Goku was read as 334, his FP at the start of Z approaches that level, like being 320 or so. Assuming things yeah)
Goku (weighted)
--- speed 228
--- power 290
-- no weights 375
Mr. Popo 340
Kami-Sama 480
Piccolo (initial) 185
-- more serious vs Kuririn 225
-- vs Shen 480
-- FP 690
Goku (FP) 700
--- Super KMHMH 910
Piccolo Bakuritsumaha 1,000
It's a mix of a scouter list with some potential liberties in regards to Radtiz scouter reading on them... Which also accounts for the theory Tao was a big deal in the 22nd Budokai.
Does it look that bad?