gulp-template | Render/precompile Lodash templates | Frontend Framework library

First thing I would change is some of your tasks like

gulp.task('scripts',gulp.parallel('templates'), scripts);

gulp.task('build', gulp.parallel('styles', 'scripts','fonts'), build);

gulp.task('run', gulp.parallel('build'), run);

Here is the task signature from the docs (https://gulpjs.com/docs/en/api/task#signature)

task([taskName], taskFunction)

You have gulp.task('run', gulp.parallel('build'), run); that last run has to be part of the argument taskFunction so you probably want :

gulp.task('run', gulp.series('build', run));

gulp.task('build', gulp.series( gulp.parallel('styles', 'scripts','fonts'), build)); and

gulp.task('scripts',gulp.series('templates', scripts));

You may have other issues but start with the above changes.