Previously working API requests no longer working

[alexteague]

We have numerous systems that have been working for at least a year making API request calls roughly every 15 minutes. Within the last two weeks or so these systems no can no longer make successful calls using the API. We're sending an HTTP Get requests with the following URL and headers(example):

https://api.weather.gov/points/33.2045,-97.0605
"ContentType", "application/x-www-form-urlencoded"
"UserAgent", "pantechdesign.com; [email protected]"
"Accept", "application/ld+json"

What we receive back is the following (cleaned up for visibility):
RESPONSE CODE: 403
Content:

<TITLE>Access Denied</TITLE>

Access Denied

You don't have permission to access "http://api.weather.gov/points/33.204,-97.06" on this server.

Reference #18.9632c717.1612481418.150882fd

Is there something we need to update in our calls to rectify this or has something changed in the API or on the server with respect to security, TLS etc. recently? We are limited to using TLS1.2.

Thanks in advance, any help is appreciated.