Update to php 7.3

I have some problems with my website now that I have updated it to php7.3 / php7.4 The frontpage has changed, I can no longer see the primary sidebar and the images have also disappeared from the text. When I click on a post it is the same again, only the frontpage I do not get it the way it was. https://packet-radio.net/ Frontpage https://packet-radio.net/kpc-non-plus/ I don't understand what's wrong now. thanks Niels