There are stringent regulations around this for public buildings, complete with formulas to calculate how many male and female toilets must be provided.
This differs from venue to venue, depending on size and type, but in general, there is usually a requirement to provide male and female toilets at a ratio of 1 to 2.
That's because women need longer, have more reasons to need a sanitary facility and are disproportionately the sex with caring responsibilities for both children and the elderly who need help and/or supervision when using the toilet.
So, anytime you see a venue has provided only mixed-sex toilets, they are extremely likely to be underproviding women unless they are providing more toilets overall than they need to as per the formula applicable to them. This is indirect sex discrimination.
As is also the case where only the women's toilets have been made mixed-sex, which leads to even more underprovision of toilets.
Please remember that unisex and mixed-sex facilities are not the same - the former are for the use of one person at a time, the latter are for the use of several people at a time. It is the latter that are the problem.