Layout 4: How to fix text size issue on mobile devices

Go to WordPress Dashboard >> Divi >> Theme Options >> Custom CSS >> add below CSS code snippet.

@media (max-width: 980px)
{
.el_md_testimonial_extended .layout4 .el-single-testimonial-card .el-testimonial-content{
padding-left: 0 !important;
padding-right: 0 !important;
}
}