@techielass, I presume you meant you:
- Copied templates ‘/user/plugins/feed/templates/(atom|feed).rss.twig’ to ‘/user/themes/my-inherited-theme/templates’
- And hard-coded the title in the copies?
By the way, I have tried all sorts of tricks to reproduce your issue, but all failed…
However…, I did notice something suspicious on your site: The url of your rss feed is https://www.techielass.com/.rss. You are missing a name in front of ‘.rss’.
(NB. Same happens for atom)
In ‘/user/themes/antimatter/templates/partials/sidebar.html.twig’, the url is set as follows:
<a class="button" href="{{ feed_url }}.rss"><i class="fa fa-rss-square"></i> RSS</a>
Looking at the url of your rss feed, it seems that ‘feed_url’ is either an empty string, or ‘/’, or null. The following code is used to set ‘feed_url’:
{% set feed_url = blog.url == '/' or blog.url == base_url_relative ? (base_url_relative~'/'~blog.slug) : blog.url %}
The value of ‘feed_url’ is based on ‘blog.slug’ (when blog is home page) or ‘blog.url’.
The only way I could force the url of the rss feed to be like ‘/.rss’, is when the ‘blog’ object is not passed to ‘partials/sidebar.html.twig’ in ‘/user/themes/antimatter/templates/blog/html.twig’:
# page is not assigned to 'blog'
{% include 'partials/sidebar.html.twig' %}
# orginal code: page is assigned to 'blog'
{% include 'partials/sidebar.html.twig' with {'blog':page} %}
You may want to have a look at that.
Anyway… the above issue does not have any effect on the <title> of the rss feed… It might be a smell of other “temporary solutions” being applied though… 
Last point:
You might want to have a look at your settings of the Asset Manager which can minify and bundle css and js files. This may improve performance by reducing the amount of bytes transferred and the amount of calls to the server.