imgやpngは表示されるのにsvgが表示されない。URLも間違ってなく、参照先のURLをブラウザで直接指定すると以下のような内容が表示される場合は
<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: Adobe Illustrator 26.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0) -->
<svg version="1.1" id="繝ｬ繧､繝､繝ｼ_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px"
y="0px" width="190px" height="36px" viewBox="0 0 190 36" enable-background="new 0 0 190 36" xml:space="preserve">
<g>
<g>
<path fill="#194180" d="M155.784,19.816c0,0-18.071,0-19.216,0c-1.296,0-2.12,0.693-2.12,1.989c0,0,0,10.504,0,11.666
c0,1.162,0.601,1.959,1.718,1.959c0,0,18.635,0,19.882,0s1.805-0.751,1.805-2.272c0,0,0-10.165,0-11.274
C157.853,20.776,156.986,19.816,155.784,19.816z M153.11,30.839h-14.041l0.03-6.676l14.012-0.031V30.839z"/>
<path fill="#194180" d="M157.579,9.611c1.174,0,2.126-0.952,2.126-2.126c0-1.174-0.952-2.126-2.126-2.126h-9.188V2.244
c0-1.029-0.834-1.863-1.863-1.863h-0.821c-1.029,0-1.863,0.834-1.863,1.863v3.114h-9.188c-1.174,0-2.126,0.952-2.126,2.126
c0,1.174,0.952,2.126,2.126,2.126h9.188v3.981h-8.549c-1.174,0-2.126,0.952-2.126,2.126c0,1.174,0.952,2.126,2.126,2.126h21.644
c1.174,0,2.126-0.952,2.126-2.126c0-1.174-0.952-2.126-2.126-2.126h-8.549V9.611H157.579z"/>.htaccessに以下の2行を追記すればOK。
AddType image/svg+xml .svg .svgz
AddEncoding gzip .svgz