There are no "legitimate concerns" about trans people.
Trans people in sport are not significantly out performing their cis counterparts.
Trans people have been using public toilets for years without incident.
Detransition is extremely rare & the most common reason for it is because of societal transphobia. Hip replacements have a greater rate of regret than trans supportive healthcare.
Puberty blockers carry no more significant risk of side effects than plenty of other medications given to children. We still give them those medications because we recognise their benefits & potential to save lives.
You don't have "legitimate concerns", you're looking for excuses to perpetuate your bias against trans people.