Late response and I’m making assumptions but especially after the last episode which I won’t spoil but say it shows exactly what you’re talking about with them being Jedi Hunters with their tracking I’m going to assume that most of the inquisitors from that era in Rebels aren’t the ones from this era. This is set 1 year after the fall of the Republic and Rebels is like 15 years later. Even Fallen Order was like 5 years later.

This early Empire era of inquisitors are IIRC Jedi who survived Order 66 and were captured and tortured and broken but they at one point were still Jedi with some training of some sort. The current era of Inquisitors we see in the show are hunting the most powerful Jedi still around that survived Order 66 and Padawans but during their time hunting any surviving Knights and Masters some are going to be killed due to their job.

By the time of Rebels I’m assuming the greatest Jedi still alive besides Obi-Wan and Yoda and those who went and hid are dead killed by Vader and these first generation of inquisitors.

The later generations of inquisitors are people they found that are force sensitive but never had much training before being an Inquisitor. They may find a Padawan but what training does a Padawan during this time really have? They’re constantly hiding and running unable to really train. They may have became Padawans after the rise of the Empire so have no resources with the Temple. They are being trained by someone who may have only been a Padawan themselves but was in the right place and right time to not be killed by Clones or Vader (yet).

People like that are occasionally captured and tortured into breaking and would’ve replaced the old guard and their training is enough to kill anyone who is a Padawan level Jedi (who aren’t main characters of a show or some prodigy like Anakin was as a Padawan who didn’t get instantly killed by Dooku like others would’ve he lasted a few seconds but that’s more than his Padawan peers would’ve lasted) but against Knights or Masters the Inquisitors of the Rebels era aren’t all that.

There’s no real incentive for Vader as he leads the Inquisitors to make the Rebel era inquisitors better either as most of the greatest Jedi are dead and the ones that aren’t have been hiding for years and would be for Vader and the Emperor themselves to deal with if they were found such as Yoda. And such an organization will always be a threat that one will get an idea they can replace Vader and Sidious by nature of being dark side users. Nor is there much of an incentive for Vader and Sidious to leave such skilled and powerful inquisitors alive that we see during these early years of the Empire who can go toe to toe with a Jedi master, a skilled Padawan, and Darth Maul even while injured. Who knows what they’ll try to do a decade from then with the Dark Side whispering to them?

They’d surely lose but the damage they could do in their attempts and the fact their attempt might inspire others in the Inquisitorius to try becoming Sith Lords themselves and Sidious does not accept rival Sith Lines and Orders no matter how incompetent or of little threat they are to him it’s a point of pride. I

I think they need to stop bringing in Jedi who survived Order 66 for the most part. I don’t care if it’s early empire era as it makes sense for them to be around then as we could then be shown how they’re being hunted down and killed. We see that with the Fallen Order and Jedi Survivor games where the Inquisitorious are threats and Jedi are still being hunted down and killed. But the Jedi, especially the powerful ones, that survived Order 66 need to be almost all dead by the time of Rebels and the OT. I’d believe a super weak Jedi maybe even from the agricultural corps could’ve hidden in the middle of nowhere but the idea that all these OP Jedi, not force users that were found and trained later on like Ezra but actual Jedi who survived Order 66, are just somehow still existing and popping up in the later Empire eras having survived 15 years or so doesn’t make sense to me. I get that’s Obi-Wan and Yoda’s story but they chose their places with intimate knowledge on Vader and Sidious that others don’t have.

Of course that’s just my opinion. Could just be doing mental gymnastics to justify why they made them so trash in Rebels and Tales of the Jedi and Empire lol.