How to solve icomoon problem?

Question

Icons

there is a long-playing prodzh. all the icons from the start decided to overtake in fonts. icons are constantly added to the font. recently there have been problems with the icomoon service. when generating (old + new svg) when replacing the fonts themselves + variables, etc.. at the output, the old icons decrease in size .. from the Nth time, it sometimes turns out to add new icons to the font and so that the old ones do not change in size. who faced this problem? I don't want to use gallp plugins, because then soon you will have to redo styles, etc. in old pages, and they have long been given to the backend