Unlike Osram, Philips Zigbee devices cannot be individually reset with a blink method. This is why SmartThings support recommends only connecting Phillips devices via a bridge. Otherwise you can get into exactly the situation you have, where the Phillips devices think they still belong to the old SmartThings hub and cannot be attached to a new coordinator.
In the US, you can solve this by buying an additional device, the Lutron remote. That can be used to reset the Hue bulbs. However, I don’t believe it’s available in Europe.
UK members have been able to do the same thing using one of two devices. There is a German-made device that works with a raspberry pi. and there are occasionally Phillips colour switches sold on eBay UK which also work.
The following thread by a UK member discusses all of these options. I would ask there if anyone has been able to use them with the strips and the bloom as well as the original bulbs.
So it is likely that you are going to have to buy an additional device in order to reset the coordinator information in the lights that you have. I think it can be done. But I don’t know if you want to spend the extra money.