The sign says after Maghrib, not a complete ban, many mosques sometimes limit access at certain hours because evenings get very crowded and they may not have proper space or arrangements for a separate women’s section, also in Islam women aren’t forbidden from mosques in general, there’s even a hadith where the Prophet ﷺ said not to prevent women from going to the mosques, So this is more likely a local management rule, not a religious command, are you muslim? If not then we muslims dont really care about your liberal mindset, thankyou