...In most parts of the UK, there has been an absence of 'that proper rain, that soaks you through' for approaching 6 weeks now. Alongside some warm sunny weather.
Established meadows tend to 'hold off' in their development at this point in the season, without regular April and May showers.
If your meadow is in year 1 (i.e. planted in 2022) then you NEED TO BE WATERING. Your plants are not established well enough to do well in dry conditions. Do a good watering, once a week. Not lots of little ones. The water has to penetrate 20cm/6 inches of soil. That takes a lot.
THE GOOD NEWS IS, HOWEVER...
...that when it rains properly (for more than 12 hours over 1-3 days) - which it inevitably will - your wildflower meadow will flourish in the sunny days that will (inevitably) follow!