Is TM getting rare ?

2 raids is hardly a reliable sample size and yes TMs are supposed to be rare.

I have gone well over a week of daily raiding with no TMs. Then I did 2, where I first got one of each and then two charged (which had never happened to me before). So it's all luck.

I get 1 TM every 5 Legendary Raids or so.

They're quite rare. Also, raid reward groups are calculated based on how many balls you get for the raid catch, so sometimes doing legendaries may actually give you a lower chance of getting better items than T3 or T4 if your team doesn't control the gym and/or doesn't get the highest damage bonus. I've occasionally had better rewards from T3s than legendaries just doing them with one other decent level teammate and claiming the gym beforehand, as opposed to being one of the highest level raiders for a legendary where most of the other players are from different teams.

TM are freaking rare since potions were added as raid reward. I didn't notice changes since that update

Not including the TM I have already use. I have 40 fast and 32 charge TM in my inventory.

By the way I do about 1 raid a day

That is normal

The higher damage bonus you and your team do, the more rewards you get from a raid drop. Stick with your team and keep grouip sizes to a minimal. If you're a higher level don't let lower levels guilt you into thinking you need to do a raid with them cause they can't handle the heat. ?