We generally try to avoid 90 degree and acute angle turns while pcb designing to avoid acid trap and reflections that may caused with high frequency signals.
For high frequency signals 90 degree turns acts as a capacitive load, which reflects signals and results in poor impedance matching… Even in low frequency signals these sharp angles may cause acid traps especially for narrow tracks.
Acid trap occurs on every PCBs especially for high density PCBs in which chemicals or etchants may get trapped in corners and reduces the width of track or may create short circuits.