I dunno, obviously you could be burnt out on Civ games in general but I think more likely there just aren't enough push/pull mechanics to keep Civ6 interesting yet. I was never a 'CIv4 > all Civs' person but honestly I went back and played a game of Civ4 and had an absolute blast. I have almost 1000 hours of Civ5 but BNW really killed the game for me (the AI was just entirely too passive leading to dull/repetitive games). And unfortunately, Civ6 seems like its closer to Civ5 in terms of AI competence and aggression.
My biggest issue other than the AI (although that is related) is that there is really no throttle on what I'm doing. I can just build cities when I want to build cities and do what I want without any mechanics or other Civs to worry about (almost everything is a soft cap which just drags things). And there isn't much to give that 'one more turn' feeling since everything is so blunted...ie, techs generally don't feel like leaps or achievements, building extra cities, ditto...it's just rote and very easy to do at will (and with very marginal returns for a very long time). Diplomacy is odd (I won't call it 'broken' like a lot of people have been slinging around), but again it's not very meaningful because quite frankly, I don't really care what the AIs are doing.
Part of the issue (but only part) is the lack of information about many mechanics...ie, I can't make informed (and thus meaningful) decisions unless I have an idea of how those mechanics I'm deciding on work. So I just pick things and go and since there is no resistance or push, it still works. So it feels like it really didn't matter what decision I made. This pertains to buildings, tech selection, civics, city planning etc. Sure I can optimize this or that given time and experience, but even on the levels I was playing Civ4 and Civ5 at, in my first game of Civ6 I'm miles ahead of the AIs and I see nothing to throttle me back or cause me to change the (probably objectively poor) decisions I made to get there.
And on the techs, they just seem to be so incremental and underwhelming in most cases. Many simply unlock a Wonder that I can't/won't build or a unit that I probably don't need or one other simple thing. There are very few that are like...omg, must decide between very desirable benefits! Civ4's tech tree was FILLED with 'must have now' choices and it feels like you made real progress when you researched many of them (not all). But you kept playing turn after turn because many of the techs were fundamental changes/upgrades with more right behind them.
I sort of got the same feeling with Civ6 that I got playing the new MOO (although I think that game is in much better shape than Civ6 is, probably due to the loooong Early Access phases where a lot changed). I play the game, it's sort of fun, but I feel like I'm just sort of going through the motions. But if I go back and play MOO2 (albeit slightly modified for balance), I'm almost immediately hooked again. Again, that feeling of "must get 'x' or 'y'" is not as prevalent in the new MOO but I feel it almost at once when playing MOO2.
At any rate, I like the core ideas of Civ6. I think they have a lot to build on. But it doesn't feel complete or internally consistent at all. There are too many rough edges and vague areas where things aren't clear how they should work. And the AI (as has been mentioned multiple times) is just not there yet. Possibly there are some simple bugs holding it back and I hope that is the case. Otherwise, I think it'll be a patch or two (and maybe some DLC) before I think Civ6 has a realistic chance to ignite the 'one more turn' feeling that I got from everything up until Civ5 BNW.
