Nashiqt

If you were excite for Keeper of the Lake, you might want to take a look at Sereno.
It is also a BL drama featuring a merman main Character from the Philippines.

The main couple of both shows is played by the same actors (Boat & Oat). so if you want to see more of this couple, I highly recommend watching this.
Based on the trailer and the omegaverse setting of Knot, the inmate scenes will probably be comparable to My Stubborn.

Otherwise most likely not a lot of similarities, in terms of story and mood, since Knot is omegaverse with a more serious mood, while My Stubborn has a lighter office setting.

same:
- both are BL
- both are about merman

difference:
- Sereno's overall mood is a bit darker than Lover Merman
- Sereno is Filipino, while Lover Merman is Thai