My HRV has been too low for 4 weeks. I think the watch is measuring wrong. I'm healthy and everything is as it was. No change in lifestyle, sleep, stress, everything ok. My Training Intensity is rather less now.
Does anyone have the same experience?

It could also be that due to less training intensity and volume, my HRV dropped, in view of these values
Several users are complaining about lower HRV values these days. Maybe it is a software…
I think the only, but quite fundamental problem is that the algorithm cannot distinguish normal physiological fluctuations from overtraining, although it can apparently handle them, see the slow decline…
10 days ago I ran a half marathon at the max (tried to break PR) and since then, it actually dropped below and stayed below
On Garmin Connect, add the nightly averages to the HRV status. This…
For marathon training for 3.40 no way 5.00 is an easy pace. Hey, Kipchoge's recovery pace is 6.20-6.30 (things might've changed, that is dated 2018-2019 (he had wr in 2018). Do you really think he is too slow?
While max HR looks really high (i'd double check that) I have a friend of mine who has similarly high, so at least reasonable. LTHR hr and tempo also sort of match.
But hr zones are no way even close to correct, as you mentioned your easy is close to your LT, that is but easy. Where did you get those numbers?
Your easy is up to 140-145, 155 is max and I'd not treat 155 as easy. And yes, you can run at 7/km and 8/km. Many new runners believe they are different (including myself), but they are not. Definitely. You'll get much better training and results if you slow down. Does take time.
Id question all these zones including LT and max HR and control those manually.
found out that if i change setting of zones to %maxHR instead of %LTHR, the zones drop an entire level. So according to %maxHR my Z2 Easy run is between 136 and 154, and based on %LTHR Z2 is between 154-168. That big diffenrence is not OK. In general LTHR will be approximately 90% of maxHR, and that is correct in my case. Something is off track here.
That sounds like it shall be. As for lthr, just typed your lthr (178 you mentioned?) To the first link I googled. Close
https://www.8020endurance.com/80-20-zone-calculator/
Ps, as your tempo run - good you felt good. Bad you developed wrong things in your body. :-)
Make a backup of the device drive on your computer before doing a complete reset.
If you copy the "Sports" back you can get your data screen setup back. See this post:
forums.garmin.com/.../some-advice-before-upgrading-replacing-a-watch-or-a-hard-reset
I assume you did a soft reset before deciding to do a full reset which as you say is frustrating to redo many settings (even given the above suggestion which does at least help a bit)