These numbers are definitely relevant, the numbers can be compared to numbers from third parties like Pentagon (US) and Institute for the Study of War and others. These are relevant because they are daily, and give insight into what’s going on currently.
We know Russia constantly makes ridiculous claims, that are quickly refuted. The same is NOT the case for Ukraine. Although it’s probably impossible to make accurate numbers, many of these numbers are actually proven, including the somewhat curious 1 sub.

Everyone knows that loss reports generated by the opposing military force are inflated,

I’m not sure we know that. Although Ukraine typically state numbers that are higher than 3rd parties state, Ukraine is also part in the action, and obviously know more and have better confirmation than any third party.
There is no evidence to my knowledge that these numbers are just propaganda. But there is clear evidence, that they are definitely NOT propaganda the same way Russia makes propaganda outright lying and denying reality.
Very often events are documented that confirm the general trend of these numbers, even if methodology should cause it to be on the high side.