Hi there, I need help with timing on a map. I'm not sure whether this map has multiple bpm's, or if the rhythm is just really wierd. At some points the bpm and offset feels completely fine, while at other times it feels like the song just says "fck the rhythm, let's put a sound here". I'm a new mapper, so this is very confusing to me. If someone could help me understand what the song is doing, that will be very much appreciated.

Link to song: https://osu.ppy.sh/s/646126

I only took a short glance is I have no interest to time that thing for you in detail.

However there are some things that make this song prone to possibly feel inconsistent:

There are many spots in which all the instruments take a break and only the vocalists keeps going.
Rule of thumb is: Vocalists are unable to hold an accurate timing on their own.
Sometimes they are on time but chances are that when the instruments (and most importantly the drums) resume playing the offset will slightly shift compared to before.
This causes you to get spots like 01:18:391 (8,1) - . Between these 2 notes everything is afloat and there is no distinct timing at all. The first drumhit on the 1 resets the offset and should therefore get an individual timing section.

Now, apart from this analysis here some instructions on how you can smooth out your timing:
Everytime the drums have a break, stop and check if they are really in time with the previous timing.
If yes, proceed to the next spot.
If no, do the following:
Remember the spot (you can put a bookmark I guess) and scroll further into the song until you have the impression that your current timing fits again. At the spot where it fits again, place an uninherited (red) timing section (shortcut is Ctrl+P). This is very important if you have a working timing for later parts of the song because once you changed the section before you don't get the offset for the later section without some effort.
Then go back to the spot where it went out of sync and start timing a new offset for that one. It may be useful to slow down the song via choosing a lower playback rate (bottom right) or placing a circle and compare it with the hitsound to make sure it is correct.
Then check if the bpm still fits. If yes, do nothing. If not, find a fitting adjustment. Based on the sections I heard, bpm does not seem to be too critical for this song though.

If these instructions don't help you, consider taking a look at the timing guide for variable timing here. Although much less sophisticated, you can approach your song the same way. And maybe it just helps you seeing someone do it instead of just reading it
Good luck!

Thank's for clearing that up, I appreciate your advice. Tried doing what you said, and i just ended up messing with the timing more. It seems the rhythm in the song just isn't very precise, it can't be helped. 01:59:408 (1,1,2,1,2) - At 1 the drummer is following the song correctly, and the next 4 drum hits are completely off rhythmically. I ended up just using sliders into sections like these to ease into the irregular rhythm. The rhythm seems to consistently be 1/16 off too early or too late. Not sure whether new timing sections is needed for that? Doing it like this sounds right, and is way easier. I think i'll just leave it as it is.

If you don't plan to get the map to ranked, doing it that way is perfectly fine.
However, for ranked maps, doing what I described above is necessary as the placement of the downbeats has to be correct in order for the map to work correctly with Nightcore/Daycore and I think also Target Practice mod.