tl;dr

OffsetDateTime
.parse( 
    "Wed, 20 Feb 2019 07:14:06 +0100" , 
    DateTimeFormatter.RFC_1123_DATE_TIME 
)
.toString()

2019-02-20T07:14:06+01:00

Details

Your problem has nothing to do with Java 8 versus Java 17.

Tip: Before blaming software that is formally specified, is thoroughly tested by enormous test suites, and is used by millions of programmers daily, suspect your own code first.

Locale

Specify a Locale. The locale determines the human language and cultural norms used in translating month names, etc.

If you do not specify a Locale, the JVM’s current default is applied implicitly. I would bet that when you ran your app at different times or on different machines, the JVM’s current default Locale varied.

Locale locale = Locale.US ;
DateTimeFormatter formatter = 
    DateTimeFormatter
    .ofPattern( "EEE, d MMM yyyy HH:mm:ss Z" )
    .withLocale( locale );
    
String input = "Wed, 20 Feb 2019 07:14:06 +0100" ;
ZonedDateTime zdt = ZonedDateTime.parse( input , formatter ) ;
String output = zdt.toString() ;
System.out.println( output );

See this code run at Ideone.com.

2019-02-20T07:14:06+01:00

RFC 1123

As commented by Ole V.V., your format happens to comply with the legacy standards RFC 1123, RFC 822, and RFC 2822.

The DateTimeFormatter class carries a pre-defined formatter object for that format. See the constant DateTimeFormatter.RFC_1123_DATE_TIME.

That pre-defined formatter already has the appropriate English-based locale required by the RFCs’ specifications. So no need to specify a Locale object here.

String input = "Wed, 20 Feb 2019 07:14:06 +0100" ;
DateTimeFormatter f = DateTimeFormatter.RFC_1123_DATE_TIME ;
OffsetDateTime odt = OffsetDateTime.parse( input , f ) ;

See this code run at Ideone.com.

2019-02-20T07:14:06+01:00

ISO 8601

Modern protocols use ISO 8601 rather than this outdated format. The java.time classes use ISO 8601 formats by default when parsing text or formatting a date-time instance.

I suggest you educate the publisher of your data about the virtues in using only ISO 8601 standard formats for communicating date-time values textually.