Strange shapes on the Wi-Fi module PCB

Probably slot antennas, you could figure out the length by the width, length and the material around it. I'm not sure if these are antennas for the wifi module or a way to null the RF from the wifi modules (I'm not an antenna expert, I mostly design things to stop RF propagation). They most likely had a electromagnetic FEM solver to design a board like this to get the right antenna pattern.

Source: https://www.sciencedirect.com/topics/engineering/slot-antenna

At RF, there is nothing as simple as a conductor. It is quite possible that these features are doing several things (improving radiation, reducing interference, at different frequencies). The design will be partly by simulation, and likely partly by comparison of a handfull of prototypes with 'variations on a theme'.

For example, #1TL looks like it could be intended as a resonant short circuit applied between the top and bottom halves of the board. In effect a notch filter for the ground plane. There are probably other reasonable explanations too.