To be honest, the various canon problems introduced by this show are the LEAST problematic aspect of the show for me. I’ve had to continuously “readjust” my understanding of Star Wars since 1999.
So now we learn Obi-Wan had this whole adventure with little 10-year-old Leia, which CLEARLY is not what you would infer from Leia’s holographic message in A New Hope. But then, in 1999 I also learned that Darth Vader created C3PO - which… doesn’t exactly contradict anything, but… like, really?
Now we know that when Obi-Wan says “Obi-Wan Kenobi? That’s a name I haven’t heard in a long time… a long time”, he means like 9 years. 9 years ago was 2013. That’s barely even yesterday, especially as you get older and time subjectively seems to move faster.
But on the other hand, after watching the Prequels, I learned that “a long time… a long time” actually just means around 19 years. Kenobi also says he hasn’t heard the name “Obi Wan” since before Luke was born, which is outright contradicted by Revenge of the Sith. Furthermore, 19 years ago was 2003. That’s certainly a “while” ago, I guess. For someone under 30 that might seem like a really long time. But it’s not “a long time… a long time” from the perspective of an old man. I mean I’m not THAT old, but 2003 doesn’t feel so long ago to me. Anyone watching Alec Guinness deliver that line in A New Hope would likely come away thinking he meant “like 40 or more years ago, maybe even centuries ago? (who knows how long these magical Jedi space Wizards can live anyway?)”
The point is, I’m so used to my natural understanding of the OT being forced to adjust or contort to fit later installments, to the extent that trying to maintain a consistent “canon” seems absurd. The only way is to be selective and maintain a personal head canon.
That said, I’m not trying to defend the Kenobi show. I think it’s tragically mediocre. But the ways it screws up canon is really the LEAST of its problems.
I would argue it does more damage than the prequels in that regard. Short of obvious flubs like Lucas forgetting that “a thousand years” and “a thousand generations” are two different things and stuff like Leia remembering her mother when RotS showed that the twins both had the exact same amount of time with her, there’s nothing that really changes or makes what comes after fundamentally unworkable. Things like Qui-Gon being Obi-Wan’s master rather than Yoda works just the same since Yoda trained all the Jedi and there’s no reason force ghost Kenobi would go into details while Luke is freezing to death on Hoth.
With this show though, you’re taking a film that has already been recontextualized out the wazoo by later films like RotJ and the prequels that it’s already packed to the brim with subtext dripping out of every line of dialogue. Adding more to that just stretches it beyond belief and stops creating substance and starts being incomprehensible.
Leia never mentioning or showing familiarity with Obi-Wan and now Luke showing unfamiliarity with lightsabers and never mentioning what happened to him as a child all comes off as unbelievable rather than plausible, even if he suffered amnesia or something after the fact, WE the audience know what happened and that little tidbit of info doesn’t actually add anything to the saga. Especially in something that is comparatively extended media compared to the film saga itself.
Couple that with a brand new character who is never mentioned in any other source being tied so intimately with each of the main characters and it reads like fanfiction. And maybe as a fanfiction it would be acceptable but a big budget Disney TV show that’s supposed to be ‘official’ canon? I’m sorry, no.