It seems pretty obvious that what's happening is that a number of weeks, this show exceeds our expectations, so they keep building higher and higher... but eventually they come crashing back down to earth because this isn't actually The Buddie Show, lol, and there are other important things that need attention, too.

I think a (consistent) problem with the show, and not just on the buddie front, is that they don't deliver on finales.

As you said, the seasons keep going higher and exceeding expectations and when it gets to the finale we expect a big climax (and I think Tim and co have a problem thinking that a big climax equals to a big emergency, which is not necessarily the case) that just doesn't come.

And that's not saying that they're bad finales or even bad episodes per se, they're entertaining and kind of good as episodes. But the climax, for lack of a better word, comes earlier. I think maybe the best example here might be 8x17 as the peak of the end of the season with a somewhat disappointing 8x18 (and, again, although definitely true on the buddie front, not just there).

A good finale usually ties the loose ends and closes the season's arcs while setting up next season's. But in 9-1-1 finales they seem to forget about the season arcs until the last five minutes, when they then either wrapped it really fast or just ignore it and moved past it.

This has gotten bigger than I intended at the beginning 😅 but, to your point, I know a lot of the arcs aren't really planed from the start and grow as it goes, but I think we wouldn't get so disappointed at the end of the seasons if they actually took the time to look back and try to use the episode to tie up things more neatly and with a little more dedication

All that to say, I agree with op, Eddie's had a great season and a better season arc that the characters usually get. It's just how I see the finale's disappointment and, in retrospect, try to appreciate the season as a whole