doc: clarify %ex whitespace behavior across versions

src/site/antora/modules/ROOT/pages/manual/pattern-layout.adoc

@@ -97,8 +97,7 @@ There is no explicit separator between text and conversion specifiers.
 The pattern parser knows when it has reached the end of a conversion specifier when it reads a conversion character.
 In the example above the conversion specifier `%-5p` means the priority of the log event should be left justified to a width of five characters.
 
-If the pattern string does not contain a specifier to handle a `Throwable` being logged, parsing of the pattern will act as if the `%xEx` specifier had been added to the end of the string.
-To suppress the formatting of the `Throwable` completely simply add `%ex\{0}` as a specifier in the pattern string.
+If the pattern string does not contain a specifier to handle a `Throwable` being logged, parsing of the pattern will act as if the `%n%ex` specifier had been added to the end of the string.
 
 [#config]
 == Configuration
@@ -176,7 +175,7 @@ If configured, the `replace` element must specify the regular expression to matc
 |Default value |`true`
 |===
 
-If `true` and the user-provided pattern does not contain an exception converter, an implicit <<converter-exception-extended,`%xEx`>> pattern is appended.
+If `true` and the user-provided pattern does not contain an exception converter, an implicit <<converter-exception-extended,`%n%ex`>> pattern is appended.
 This means that if you do not include a way to output exceptions in your pattern, the default exception formatter will be added to the end of the pattern.
 Setting this to `false` disables this behavior and allows you to exclude exceptions from your pattern output.
 
@@ -603,7 +602,12 @@ In this mode, the exception stack trace will be rendered according to the config
 
 [IMPORTANT]
 ====
-All rendered exception stack traces are ensured to be prefixed with a new line obtained using `System.lineSeparator()`.
+Earlier versions of Log4j Core always inserted a space between the *output* of the previous conversion specifier and the stack trace.
+Starting with version `2.25.0`, this was changed to a line separator instead of a space.
+Since version `2.25.2`, automatic separation occurs *only* for converters implicitly added via the <<plugin-attr-alwaysWriteExceptions>> option.
+
+When you add a throwable converter explicitly in your pattern, Log4j Core no longer inserts any separator on its own: you have full control over whether and how to separate the stack trace from the preceding message.
+Thus, if you explicitly provide an exception stack trace converter (e.g., `%ex`), and want to prefix it with a newline, you need it add the newline prefix yourself too (e.g., `%n%ex`).
 ====
 
 link:../javadoc/log4j-core/org/apache/logging/log4j/core/pattern/ThrowablePatternConverter.html[`ThrowablePatternConverter`] specifier grammar **for rendering stack traces**: