Experience fragment fails in plain mode

[nbg62]

I'm trying to open weekend xf from publisher instance on Cloud sandbox using plain notation

it works using

/content/experience-fragments/wknd/us/en/featured/camping-western-australia/master.html

but fails with plain

/content/experience-fragments/wknd/us/en/featured/camping-western-australia/master.plain.html

Note that WKND project is deployed without dispatcher config (which fails during deployment), not sure if this is connected.

Error

*ERROR* [109.245.223.249 [1666194957543] GET /content/experience-fragments/wknd/us/en/featured/camping-western-australia/master.plain.html HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught Throwable
java.lang.StringIndexOutOfBoundsException: begin 0, end -1, length 86
at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3319)
at java.base/java.lang.String.substring(String.java:1874)
at com.adobe.cq.xf.impl.render.handler.PathAttributesHandler.processSrcAttr(PathAttributesHandler.java:97) [com.adobe.cq.cq-experience-fragments:1.3.66]
at com.adobe.cq.xf.impl.render.handler.PathAttributesHandler.handle(PathAttributesHandler.java:61) [com.adobe.cq.cq-experience-fragments:1.3.66]
at com.adobe.cq.xf.impl.render.HtmlTransformer.startElement(HtmlTransformer.java:117) [com.adobe.cq.cq-experience-fragments:1.3.66]
at org.apache.cocoon.xml.sax.AbstractSAXPipe.startElement(AbstractSAXPipe.java:97) [org.apache.cocoon.cocoon-xml:2.0.2]
at com.day.cq.mcm.core.newsletter.NewsletterTransformerFactory$NewsletterTransformer.startElement(NewsletterTransformerFactory.java:132) [com.day.cq.mcm.cq-mcm-core:5.13.4]
at com.adobe.cq.xf.impl.render.JsoupHtmlGeneratorFactory$JsoupHTMLGenerator.processNode(JsoupHtmlGeneratorFactory.java:109) [com.adobe.cq.cq-experience-fragments:1.3.66]
at com.adobe.cq.xf.impl.render.JsoupHtmlGeneratorFactory$JsoupHTMLGenerator.processNode(JsoupHtmlGeneratorFactory.java:110) [com.adobe.cq.cq-experience-fragments:1.3.66]

[kautuk_sahni]

 @ManviSharma @Esteban666 @Sady_Rifat @partyush @Shivanandh @B_Sravan @ksh_ingole7 @Pawan-Gupta @SivakumarKanoori 

I would greatly appreciate it if you could spare a moment to review this AEM question and share your expert insights. Additionally, if you could provide any guidance to the author in addressing the problem, it would be immensely helpful.