Besides not knowing about the dimensions, substrate relative permittivity $e_r$ and backside ground yes/no my guess from the picture is that the transmission line is a microstrip line and not a coplanar line.
Front sides of the microstrip line printed circuit boards often also have ground metal, but that's for shielding or just practical etching reasons and does not impact the transversal electromagnetic wave mode.
However just from the front side these may be mistaken as coplanar lines. I would always check the backside for that reason (still there is no definite prove, but another clue).
Anyway for both transmission lines at bends you get a parallel capacitance to ground due to the fringing fields causes by the sharp inner and outer edges.
That capacitance can to be compensated by adding inductance:
The compensating inductance can be achieved by a narrowed line, e.g. phase cutting the outer edge.
For microstrip lines you can either simulate the compensated bend with e.g. sonnet lite or calculate it with an approximation formula as given by e.g. Microwaves101 Mitered bends:
$D = W* \sqrt{2}$ (the diagonal of a "square" miter)
$X= D* (0.52 + 0.65 e^{-1.35 * (W/H)})$
$A = ( X- D/2) * \sqrt{2}$
W, H being width and height of the microstrip line.
For actual coplanar lines the compensation is more complex as you have to make sure the slot mode is not excited.
Here are two links describing such an option:
Wire-Bond Free Technique for Right-Angle Coplanar Waveguide Bend Structures
Coplanar waveguide bend with radial compensation
For these I presume EM simulation is mandatory and you won't get good approximation formulas.
Finally, when there is enough area you can also form a wide radius circle segment to smoothly bend without having to compensate - for both lines.
But that is often prevented due to cost and losses by the additional line length.
