This feed does not validate.
<width>270</width> <!-- add your logo's width (px) then remove this comm ...
^
<font color="#000000"><b> - <br><br>select sum(tax_rate) as tax_rate from ta ...
... ="#ff0000">[TEP STOP]</font></small><br><br></b></font>
^
In addition, interoperability with the widest range of feed readers could be improved by implementing the following recommendations.
<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
<channel>
<title>Paweł R. Stań</title>
<link>http://sklep.spojrzenie.com.pl</link>
<description>Spojrzenie Sklep Ezoteryczny</description>
<!--<atom:link href="http://sklep.spojrzenie.com.pl/rss.php?manufacturers_id=20" rel="self" type="application/rss+xml" /> Remove comments if you want this to remain -->
<webMaster>sklep@spojrzenie.com.pl ()</webMaster>
<language>pl</language>
<lastBuildDate>Mon, 12 Apr 2021 09:33:18 GMT</lastBuildDate>
<image>
<url>http://sklep.spojrzenie.com.pl/gfx/logo-spojrzenie-n3.png</url> <!-- upload and replace name of your logo file -->
<title></title>
<link>http://sklep.spojrzenie.com.pl</link>
<description>Spojrzenie Sklep Ezoteryczny</description>
<width>270</width> <!-- add your logo's width (px) then remove this comment -->
<height>55</height> <!-- add your logo's height (px) then remove this comment -->
</image>
<copyright>Copyright 2015, Binaural Poland</copyright> <!-- add your copyright info then remove this comment -->
<docs>http://blogs.law.harvard.edu/tech/rss</docs>
<font color="#000000"><b> - <br><br>select sum(tax_rate) as tax_rate from tax_rates tr left join zones_to_geo_zones za on (tr.tax_zone_id = za.geo_zone_id) left join geo_zones tz on (tz.geo_zone_id = tr.tax_zone_id) where (za.zone_country_id is null or za.zone_country_id = '0' or za.zone_country_id = '170') and (za.zone_id is null or za.zone_id = '0' or za.zone_id = '185') and tr.tax_class_id = '2' group by tr.tax_priority<br><br><small><font color="#ff0000">[TEP STOP]</font></small><br><br></b></font>